1. Field of the Invention
The present invention relates to a monitoring apparatus for an electronic key and a displaying apparatus for positional information on an electronic key. Particularly, it relates to a monitoring apparatus for an electronic key and a displaying apparatus for positional information on an electronic key, which are capable of displaying positional information on the electronic key in a GPS navigation unit mounted on a movable body.
2. Description of Background Art
There is a known portable type transmitter-receiver, which receives a request signal from a control unit mounted on a vehicle and which transmits a reply signal of this request signal, i.e., an electronic key used for a vehicle. For example, in an electronic key system disclosed in Japanese Patent Laid-open Publication No. 2001-349110, a control unit on a vehicle verifies identification information contained in a reply signal in response to a request signal with pre-registered identification information, and a door is unlocked at the stage where these pieces of identification information coincide with each other. Moreover, the electronic key system is configured such that upon operation of an ignition knob, a communication for enabling an engine to start is carried out between a control unit and the electronic key. If these pieces of identification information coincide with each other also in the verification of the identification information carried out via this communication, then the engine starts.
Unlike a conventional key used by being inserted into a key hole of a vehicle, the electronic key may be lost because the electronic key functions without being physically connected to a car body. Even if the electronic key is dropped, in vehicles such as a four-wheel vehicle having a cabin, the electronic key would less likely fall out of the cabin and be lost. However, in motorcycles, all-terrain vehicles (ATV), or the like, which do not have a cabin, if the electronic key is dropped, these vehicles would most likely run away leaving the electronic key on the road, or the like.
Then, the present inventor proposed an electronic key system, wherein a warning is outputted when there is no response to a request signal outputted when the start switch of a vehicle is on (Japanese Patent Laid-open Publication No. 2004-114860). According to this system, when the electronic key is outside the communication range of the vehicle, in other words, when the vehicle travels leaving the electronic key on the road, or the like, a warning indicating as such is given. Therefore, an advantage is that the lost electronic key can be found just stopping the vehicle immediately and searching within a limited range.
According to the system described in Japanese Patent Laid-open Publication No. 2004-114860, the location where the electronic key is lost can be limited to some extent for search. However, a driver may keep on traveling without noticing the warning. In this case, the range to be searched will be wider, and the electronic key may not be found. Thus, a system is expected, in which the electronic key can be found out within a limited range of search.